Using Quantitative TEM Analysis of Implant Damage to Study Surface Recombination Velocity in Silicon

Abstract

AbstractSilicon wafers with shallow trench isolation structures 3700Å deep were self-implanted with silicon at 40keV, and a dose of 1E15/cm2. This produced an amorphous layer 1000Å deep. The samples were subsequently annealed at temperatures ranging from 750°C to 900°C. The excess interstitials can recombine at the “surface” created by the proximity to the trench sidewall. Plan-view TEM was used to quantify the dislocation distribution as a function of distance from the trench sidewall. It was found that there was no measurable change in defect density as a function of distance from the trench. This was true for both the 20 minute isochronal anneal, and the isothermal study 750°C. This suggests there is a relatively weak recombination of interstitials at the surface. This is surprising given most of the TCAD models assume a very fast surface recombination velocity.